三七总皂甙对牛血清白蛋白溶液构象的影响

应用衰减全反射傅立叶变换红外光谱结合荧光光谱和紫外光谱研究了中药三七 的有效成分三七总皂甙与牛血清白蛋白（BSA）的相互作用，采用对蛋白质红外光 谱酰氨Ⅰ带和酰氨Ⅲ带进行曲线拟合的方法，定量分析了不同浓度三七总皂甙对 BSA二级结构的影响，发现随着三七总皂甙浓度的增加，蛋白分子结构逐渐发生了 由螺旋向折叠的转化。a-螺旋结构减少了3%，β-折叠结构增加了约5%，其它二级 结构没有明显的变化，红外差谱和荧光光谱的结果为药物与蛋白质的作用引起牛血 清白蛋白溶液构象的变化提供了佐证，紫外光谱反映了单体皂甙与蛋白质的结合常 数的差异。

Influence of Total Saponins of Panax notoginseng on the Conformation of BSA

The interaction between total saponins of Panax notoginseng (TSPN) and bovine albumin serum (BSA) was investigated by FT-ATR-IR combined with fluorescence and ultraviolet spectroscopy. The difference IR spectra before and after the interaction between drug and protein and fluorescence quenching of BSA provided the evidences of conformation changes of BSA. The binding constants of two saponins with BSA were determined by ultraviolet spectra. The varieties of BSA secondary structure after binding with TSPN were analyzed quantitatively by curve-fitting of amide I and amide IE bands. The results showed that theα-helix structure of BSA was decreased about 3% and theβ-sheet was increased about 5% with the increasing of TSPN concentration, but the other structures were almost unchanged. The reduction of the α- helix in favor of theβ-sheet structure is indicative of a partial unfolding of protein in the presence of TSPN at a high drag concentration.